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Old 17-09-2007, 11:02 AM
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White balance lense cap? (modded 300d)

Hi Guys,

I'm looking at getting one of these for the modded 300D since it is too red so i can custom white balance properly each time. Are these any good? has anyone tried this?

cheers
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Old 17-09-2007, 11:30 AM
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sounds interesting, and no I havent tried it.
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Old 17-09-2007, 11:52 AM
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hey houghy, do you CWB your moddedd 350d when taking astro pics? or you leave it set to AWB?
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Old 17-09-2007, 12:01 PM
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there is a review here

http://l7foto.com/2007/05/31/white-b...ns-cap-review/
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Old 17-09-2007, 12:06 PM
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Quote:
Originally Posted by EzyStyles View Post
hey houghy, do you CWB your moddedd 350d when taking astro pics? or you leave it set to AWB?
no leave it on AWB, but I should custom white balance it, although how do you do that for low light situations?
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Old 17-09-2007, 12:26 PM
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arh thanks paul for the link. I was wondering, since it is modded, red channel will be enhanced thus when taking astro images, it will turn out overly red unless you process the crap out of it. Normally, you put a piece of white paper under sunlight, take a shot using standard lense, then use that pic to set it as CWB. I have been doing that which makes it a huge difference. The white balance lense cap will be more constant and accurate.
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Old 17-09-2007, 12:46 PM
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It is meaningless to compensate for white balance with astro images. Signal is signal and how you put it together for a final image is almost purely what you think the object looks like from the last image you think you saw.

The filter in front of the sensor of modern digital cameras tries to modulate the sensors spectral sensitivity to match the human eye sensitivity. The further complicating factor is the ambient illumination which can shift colour balance. Our eyes do this automatically!
This is what colour balance attempts to do.

Removing the filter to 'modd' the camera makes it far more sensitive in the far red to pick up HA which we can barely perceive. So if you then balance again you lose HA sensitivity so defeating the reason for removing the filter in the first place.

If you worry that your red histogram is way higher than green or blue just do what I do, ignore it!

Setting the colour temperature to 4000K when converting from RAW to TIFF will compensate without losing data in the red channel!

Bert

Last edited by avandonk; 17-09-2007 at 03:11 PM.
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Old 17-09-2007, 12:48 PM
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Quote:
Originally Posted by [1ponders] View Post

I think that this cap is nothing more than just matte glass... anyone can make it from cheap UV filter, with a help of some grinding powder.
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Old 17-09-2007, 02:04 PM
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I used an expodisc the other night. It gave me SPOT ON white balance. They're pricey up in the $100USD range, but well worth it.

http://www.topicify.com/goo.jpg

SPOT ON WHITE BALANCE!
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Old 17-09-2007, 04:10 PM
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I thought by just removing the stock IR filter, that already in itself improves HA emission. how would balancing colours using CWB decreases this? *shrugs, i just dont' get it*.

I haven't notice any difference using the modded 300d in AWB and CWB, only thing is that CWB i think personally, is better balance in colours and less processing involved.

Last edited by EzyStyles; 17-09-2007 at 04:23 PM.
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Old 17-09-2007, 06:30 PM
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I always use CWB for my astro shots..Like you mention it makes it much easier to get your color balance close and in processing..I find it gives me a more pleasing image color wise..but that has alot to do with personal taste as well..
when I first modded the camera I did some experiments with AWB and CWB and CWB won out for me.. I couldn`t see any difference in Ha sensitivity only differences in color balance..
cheers
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Old 17-09-2007, 07:56 PM
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hey gary, your M20 Triffid image.... that is a fine example what i called correct colour balancing. is it possible to post your CWB image so i can get a fair idea what i should be aiming for?

cheers
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Old 17-09-2007, 08:08 PM
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there not worth for what they cost imo, its just a translucent colorless peice of plastic.

you can replicate the same effects using a $10 collapsible translucent diffuser, and you can allso use that diffuser to diffuse macro subjects.

or even a colorless greycard, white papper or black papper
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Old 18-09-2007, 07:28 AM
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Quote:
Originally Posted by EzyStyles View Post
hey gary, your M20 Triffid image.... that is a fine example what i called correct colour balancing. is it possible to post your CWB image so i can get a fair idea what i should be aiming for?

cheers
No probs Eric! I have it somewhere on this pc as I remember keeping it...
I shall post when I find it .
cheers
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Old 18-09-2007, 02:28 PM
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Here it is Eric!
I think this is what I am still using for my CWB.
cheers Gary
Attached Thumbnails
Click for full-size image (canon-300d CWB.JPG)
118.4 KB14 views
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Old 18-09-2007, 04:56 PM
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cheerss gary! many thanks for that. I might actually use yours for my CWB see how it turns out.

thanks again.
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Old 18-09-2007, 10:58 PM
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www.expodisc.com

I use it all the time for my pro-photography work and it never fails.

note: not for the light wallet though.. i think a 77mm one cost me like $170
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Old 19-09-2007, 10:27 AM
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Quote:
Originally Posted by Benny L View Post
www.expodisc.com

I use it all the time for my pro-photography work and it never fails.

note: not for the light wallet though.. i think a 77mm one cost me like $170
Yep, best white balance I've ever gotten.

1D Mark IIn - Canon 70-200mm F2.8L IS
http://www.topicify.com/goo.jpg
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